Tune-Up Specifications

The following specifications are published from the latest information available. This data should only be used in the absence of a decal affixed in the engine compartment.


Engine, Liter/CID 4.0L/6-242
Spark Plug Gap, Inch 0.035

Ignition Timing

Fig. B:

Firing Order [03] As Shown
Man. Trans. [04]
Auto. Trans. [04]
Mark Location Damper

Curb Idle Speed [02]
Man. Trans. [04]
Auto. Trans. [04]

Fast Idle Speed
Man. Trans. [04]
Auto. Trans. [04]

Fuel Pump Pressure, psi 31, [01]
Valve Lash, Inch [05]


BTDC -- Before Top Dead Center.

[01] -- With a suitable fuel pressure test gauge connected to pressure test port on fuel rail.
[02] -- On models equipped with manual transmission, idle speed is adjusted in Neutral on models equipped with automatic transmission, idle speed is adjusted in Drive (D). When checking idle speed, set parking brake & block drive wheels.
[03] -- Before removing wires from distributor cap, determine location of No.1 wire in cap, as distributor position may have been altered from that shown at the end of this chart.
[04] -- Refer to vehicle emission control label for ignition timing & idle speed information.
[05] -- Non-adjustable.